ساختار و جذب سيال الكتروليت درون نانوپيپت، كشش سطحي، فشار و قواعد مربوط به آن براي سيالات كره‌ي سخت و لنارد- جونز در نانوحفره‌ها با تقارن كروي با استفاده از نظريه‌ي تابعي چگالي

چكيده انگليسي :

Structure and adsorption of electrolyte in the nanopipet pore Interfacial tension pressure and related regularities for hard sphere and lennard Jones fluids in the nanopores with spherical symmetry by using density functional theory Razieh Rabiei Dehnavi r rabiei@ch iut ac ir June 2019 Department of Chemistry Isfahan University of Technology 84156 83111 Isfahan Iran Supervisor Ezat Keshavarzi keshavrz@cc iut ac ir Advisor Nader Karimi Advisor Abbas Helmi Department of Chemistry Isfahan University of Technology 84156 83111 Isfahan Iran Department of Electrical Computer Engineering Isfahan University of Technology 84156 83111 Isfahan IranAbstract The best version of DFT MFMT was employed to investigate the structure and properties of confinedfluids in nanopores with different geometries This work has two different sections electrolyte in nanopipet andnon electrolyte in nanopores with spherical symmetry In the first section to solve the electrolyte problem inDFT approach at first we investigated the behavior of hard sphere fluid inside and around nanopipet pores Ourfindings showed that fluid molecules have a strong tendency to accumulate at the conical part of the nanopipte For the cone region contact density at the concave wall decreases with the radius of its cross section A reversebehavior is however observed for fluid density at its convex wall Also a pronounced maximum peak observedfor contact density of fluids in the pore in the junction of two parts of a nanopipet truncated cone andcylindrical section Comparison of fluid adsorption in nano cylindrical with nano truncated cone pores ofidentical volumes reveals that the cylindrical nanopores record higher adsorption values than conical nanoporesfor reduced integer values of tip radius Finally we studied the structure of electrolyte in the nanopipet andinvestigated the effect of nanopore size and concentration of bulk fluid on it In the second section of this work we studied the properties of fluids in the bispherical and spherical nanopores This section has two parts In thefirst part the effects of structure of fluid on the values of wall pressure and interfacial tension of hard and LJfluids at the wall of a spherical guest particle were investigated Results showed that confinement mainly causedoscillations in these parameters around their corresponding bulk values The amplitude of the oscillationsincreased with increasing density but with decreasing pore size Maximum heights of the oscillations wereobserved for both properties at each density when the pore size was around 2 times in molecular diameter Moreover it is found that kind of interactions of the guest particle with the fluid determine the behavior ofinterfacial tension with guest particle size In the second part using statistical thermodynamics and the DFTapproach local normal and tangential pressures are determined for LJ fluids in spherical and bisphericalcavities Both pressure components are observed to exhibit an oscillatory behavior in the sense that theiramplitudes increase with increasing density and decreasing cavity size Also the values for density andtangential pressure at the concave wall of hard bispherical pores are larger than those at the convex wall Opposite results are obtained when a strong attraction potential is applied to the convex wall while the concavewall is a hard one Although these two factors drastically affect the local density pressures and their averagevalues the behavior of the average values of their thermodynamic properties does not depend on them Oneaspect of the study involves an investigation of the validity of certain well known bulk regularities for LJ fluidsin spherical and bispherical cavities These regularities include common compression point linear relationbetween pressure and temperature for each isochors common bulk modulus point and the Tait Murnaghanequation These regularities are studied for both pressure components and their relevant properties All the fourregul

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نانوپيپت , نانوحفره هايي با تقارن كروي , سيال محدود شده , تنسور فشار , قواعد ترموديناميكي , نظريه‌ي تابعي چگالي